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In this communication, an atmospheric one-step plasma-based method is reported for the simultaneous synthesis and deposition of robust redox-active catechol-rich polymers. The bioinspired films are characterized by combining various analytical techniques, including IR, XPS, AFM and SIMS, and their potentials as organic cathode materials for lithium ion battery demonstrated. The influence of the coating thickness on the applicative properties of the films is also investigated.

Here, we describe a robust process aiming at conferring antibacterial properties on stainless steel through the covalent grafting of nisin, a natural antimicrobial peptide, onto a functional plasma thin film deposited by an atmospheric pressure dielectric barrier discharge process. The three different steps of the procedure, namely the deposition of a carboxyl rich thin layer, the surface activation by using a zero-length crosslinking agent and the nisin immobilisation, are reported and thoroughly characterised. A correlation between the carboxylic group surface concentration and the surface roughness onto the antibacterial properties of the layers is evidenced. Finally, IR analyses appear as a powerful analytical tool allowing us to validate the different chemical surface modifications, to confirm the relevance of the activation step to achieve a stable and homogenous peptide grafting over all the surfaces, as well as to investigate the secondary structure of immobilized peptides.

The growth of thermoresponsive layers with the atmospheric pressure plasma-initiated chemical vapor deposition (AP-PiCVD) process is reported for the first time. N-vinyl caprolactam (NVCL) was successfully homopolymerized and copolymerized with ethylene glycol dimethacrylate (EGDMA), yielding water-soluble and water-stable thermoresponsive thin films, respectively. Strong chemical retention and high thermoresponsivity were achieved, highlighting the ability of AP-PiCVD to grow functional conventional homopolymers and copolymers.

Prevention of bacterial adhesion and biofilm formation on the surfaces of materials is a topic of major medical and societal importance. In this study, an up-scalable atmospheric-pressure plasma assisted deposition method is introduced to produce a multicomponent coating towards the elaboration of antibacterial and anti-biofilm surfaces. Interestingly, from a single catechol-based monomer, high deposition rates of highly chemically reactive functional thin films bearing catechol as well as quinone groups are achieved. The catechol-bearing thin film allows the in situ silver nanoparticle formation, assessed by scanning electron microscopy and EDX, whilst the enriched-quinone thin film is exploited for immobilizing dispersine B, an enzyme. In vitro functional assays demonstrated the dual antibacterial and anti-biofouling resistance properties of the coatings due to the antibacterial effect of silver and the fouling resistance of grafted dispersine B, respectively. Surfaces coated only with silver provide an antibacterial effect but fail to inhibit bacterial attachment, highlighting the usefulness of such dual-action surfaces. The approach presented here provides a simple and effective chemical pathway to construct powerful antibacterial surfaces for various industrial applications.

In this work, an atmospheric aerosol assisted pulsed plasma process is reported as an environmentally friendly technique for the preparation of tunable catechol-bearing thin films under solvent and catalyst free conditions. The approach relies on the direct injection of dopamine acrylamide dissolved in 2-hydroxyethylmethacrylate as comonomer into the plasma zone. By adjusting the pulsing of the electrical discharge, the reactive plasma process can be alternatively switch ON (tON) and OFF (tOFF) during different periods of time, thus allowing a facile and fine tuning of the catechol density, morphology and deposition rate of the coating. An optimal tON/tOFF ratio is established, that permits maximizing the catechol content in the deposited film. Finally, a diagram, based on the average energy input into the process, is proposed allowing for easy custom synthesis of layers with specific chemical and physical properties, thus highlighting the utility of the developed dry plasma route.

Liquid-assisted plasma-enhanced chemical vapor deposition (LA-PECVD) provides a convenient approach toward the preparation of functional surfaces. In this work, the LA-PECVD approach is reported for the high deposition rate of tuneable catechol and quinone-functionalized coatings from plasma polymerization of vinyltrimethoxysilane (VTMOS) and dopamine acrylamide (DOA). Most particularly, the influence of the liquid precursor delivery rate and of the plasma power density on the chemistry and morphology of the formed layers are investigated. Precursor delivery rate and plasma power conditions are found, through mass measurement, XPS, FTIR, and Raman spectroscopy, to enable the high deposition rate of cross-linked coatings. Interestingly, the integration and conservation of the catechol functional group from the DOA monomer are highlighted through the reduction of a silver nitrate solution and silver nanoparticles formation observation via SEM/EDX. Due to the presence of oxidant species and to the bombardment of the layer with highly energetic species, quinone groups formation is likely to occur during the plasma treatment and is then highlighted via ToF-SIMS analyses of a surface successfully derivatized with a β-lactamase. The conservation of both functional groups on the surface makes this type of layer promising for numerous applications. Quinone groups provide a real platform for the immobilization of biomolecules with various properties, e.g., antibiotics degradation, antibacterial, while the catechol groups are interesting for trapping radicals or metal ions for water treatment applications.

The deposition of polymeric thin layers bearing reactive functional groups is a promising solution to provide functionality on otherwise inert surfaces, for instance, for bioconjugation purposes. Atmospheric pressure plasma (AP plasma) deposition technology offers many advantages, such as fast deposition rates, low costs, low waste generation and suitability for coating various kind of material surfaces. In this work, the AP plasma-assisted copolymerization of methyl methacrylate (MMA) with a vinyl derivative of L-DOPA was studied in order to deposit coatings with reactive catechol/quinone groups suitable for protein covalent immobilization. The effect of adding a chemical cross-linker, between 0 and 2 mol%, to the monomer mixture is also studied in order to prepare robust plasma PMMA-based layers in liquid physiological media. The layer prepared with 0.2 mol% of cross-linker shows the best balance between stability in saline-buffered media and surface functionalization. Bioconjugation via the grafting of Ranaspumin-2 recombinant, a naturally occurring surfactant protein, is carried out in a single step after plasma deposition. Protein immobilization is corroborated by Quartz Crystal Microbalance with Dissipation (QCM-D) and Surface Plasmon Resonance (SPR) analyses and confirmed via Epicocconone staining, X-Ray Photoemission Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) measurements and surface wettability characterizations. The bio-functionalized layers presented an enhanced activity against the adhesion of Human Serum Albumin (HSA), indicating the grafting potential of the Ranaspumin-2 bio-surfactant to produce anti-biofouling functional coatings.

In this work, an atmospheric-pressure dielectric barrier discharge process is exploited for the fast deposition of adherent epoxy-rich layers acting as a versatile platform for the efficient one-step biomolecule immobilization in mild aqueous conditions. Particular attention is given to the influence of the plasma process parameters on the chemical and morphological properties of the deposited layers and on their subsequent exploitation for chemical interfacial reactions. As a proof-of-concept, two enzymes with drastically different biological properties, namely dispersin B and a laccase, are immobilized onto functionalized metallic surfaces. The pH of the enzyme solution appears as a key parameter to control the amount of immobilized enzyme on the plasma functionalized surfaces, thus leading to bioactive surfaces with improved stability and activity.

Bioconjugation of enzymes on coatings based on polydopamine (PDA) layers is an appealing approach to control biological responses on biomedical implant surfaces. As alternative to PDA wet deposition, a fast, solvent-free, and dynamic deposition approach based on atmospheric-pressure plasma dielectric barrier discharge process is considered to deposit on metallic surfaces acrylic-based interlayers containing highly chemically reactive catechol/quinone groups. A biomimetic approach based on covalent immobilization of Dispersin B, an enzyme with antibiofilm properties, shows the bioconjugation potential of the novel plasma polymer layers. The excellent antibiofilm activity against Staphylococcus epidermidis is comparable to the PDA-based layers prepared by wet chemical methods with slow deposition rates. A study of preosteoblastic MG-63 human cell line viability and adhesion properties on plasma polymer layers demonstrates early interaction required for biomedical applications.

Herein, plasma deposited thermally responsive thin polymer films from N-vinylcaprolactam (NVCL) is reported for the first time by using a low pressure RF plasma process. While FT-IR and XPS analyses highlight the film chemistry, ToF-SIMS combined with MALDI-MS analyses allow to accurately identify different oligomer distributions in the deposited film. The switching behavior of these smart surfaces is confirmed with water contact angle measurements at low and high temperatures, allowing also to estimate the Lower Critical Solution Temperature.

The objective of this work is to investigate a novel top–down synthesis route toward the elaboration of nanopatterned polymer surfaces by combining thin polymer structuring (polymer-demixing) and plasma etching techniques. Thanks to this original approach, the adjustment of the parameters during the wet chemical and plasma steps allows independent tuning of the lateral dimension of the polymer structures (diameter) and the height of the pillars. The nanopatterning description of two different polymers, namely polyethylene naphthalate and polyimide, is reported. Johnson–Kendall–Roberts (JKR) adhesion tests are carried out to compare the adhesive property of the patterned and non-patterned polymer surfaces. These measurements allow highlighting the importance of the polymer viscoelasticity for future development of bio-inspired polymer-based dry adhesives.

In this paper, we report a new and easily up-scalable dry chemical method to functionalize with diene and dienophile groups a large range of surfaces, such as metal, polymer, or glass, and we demonstrate the potentiality of this technique to realize thermally responsive adhesion between these materials. A complete and extensive surface chemistry analysis of the grafted surfaces, based on the deposition of an anhydride-rich thin plasma polymer layer by using an atmospheric pressure dielectric barrier discharge (DBD) plasma process, and its subsequent gas phase aminolysis reaction with specific diene or dienophile compound is discussed. The optimization of the assembling condition for these tailored surfaces has led to achieve a Diels-Alder adhesion force up to 0.6 N/mm at ambient temperature, which can be reduced by a factor of 50 when the retro Diels-Alder is ignited at a heating temperature around 200 °C. The study of the failure interface produced after peeling tests is presented and a mechanism of failure is proposed, based on forensic analyses involving surface analytical techniques such as XPS, ToF-SIMS, and SEM combined to AFM analyses for the retrieving of chemical and morphological information.

Atmospheric pressure dielectric barrier discharge codeposition of maleic anhydride and vinyltrimethoxysilane on aluminium foil was investigated. The layers, characterised by Scanning Electron Microscopy, Fourier-Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy, have been successfully functionalised with diene groups. This could be useful to work out reversible adhesion.

In order to functionalize silicon carbide nanopowders with carboxylic groups, an r.f. (13.56 MHz) low pressure plasma reactor has been developed so that particles can be stirred during the processing to try to coat them on their whole surface. Coatings in an O 2 /hexamethyldisilazane (HMDSN) mixture have first been optimized on flat substrates; X-ray Photoelectron Spectroscopy (XPS) analysis showed that the O 2 /HMDSN gas mixture resulted in a coating evolving from a polymer-like structure to a more inorganic SiO x -like structure as the oxygen ratio increased. For a large O 2 /HMDSN value, carboxylic groups were detected on the sample surface. Silicon carbide nanoparticles have then been plasma processed in such a reactive atmosphere. XPS, Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Transmission Electron Microscopy (TEM) analyses evidenced the surface modification of the processed powder and confirmed the grafting of carboxylic groups.

International audience; Plasma processes, mostly involving so-called "thermal" plasmas, have been exploited in many instances for the gas phase synthesis of carbon nanoparticles such as carbon black, fullerenes or carbon nanotubes. A non-thermal plasma process, based on low current-high voltage discharges, has been developed for the gas phase synthesis of carbon nanoparticles at atmospheric pressure. This process can produce a broad range of products such as furnace-type carbon blacks, acetylene-type carbon blacks, and nanoparticles with a peculiar morphology that we call "crumpled paper sheets". The products were characterized by scanning and transmission electron microscopy, X-ray diffraction and BET measurements. Some correlations between the operating conditions and the characteristics of carbon nanostructures highlight temperature as a key parameter for controlling the growth, formation, and type of the nanoparticles obtained.

A natural vulcanized rubber was treated by atmospheric dielectric barrier discharges to improve its adhesion to silicone adhesive. The different operating conditions were: (i) the nature of the plasma gas associated or not with organic precursors such as acetic acid or allyl alcohol, (ii) the concentration of the precursors in the gas phase, (iii) the power discharge (between 500 and 1 000 W) and (iv) the treatment time (between 18 and 30 s). The surface modifications induced by the plasma treatments were characterized by water contact angle measurements and XPS analyses. T-peel tests were carried out to evaluate the influence of the surface modifications on the adhesion properties of the treated rubber. The efficiency of plasma treatments with the use of allyl alcohol has been proved for the adhesion improvement of natural vulcanized rubbers to a silicone adhesive (increase by a factor of 10). XPS analysis revealed that this treatment induced an increase of the total oxygen amount in the sample with the preferential formation of CO bonds, which might explain the adhesion improvement observed.

Adhesion of epoxy resins on copper foils for printed circuit board (PCB) applications is improved by nearly a factor of 5, using surface cleaning and deposition of a 15-nm-thick film in a low-pressure remote plasma-enhanced chemical vapor deposition process. The cleaning pretreatment, using an N2–O2 oxidizing gas mixture with moderate heating (343 K), gives the best results. This pretreatment removes the carbonaceous contaminants present on the topmost surface of the sample and slightly oxidizes the copper into CuO. This oxide is then reduced during the deposition treatment, presumably by reaction with the aminopropyltrimethoxysilane (APTMS) precursor. The surface roughness is unchanged after treatment, thereby showing that the improvement of the copper/epoxy adhesion is only due to the chemistry of the plasma coating. Applying these results to dielectric barrier discharges allows us to achieve the same level of adhesion, which, therefore, does not depend on the process.

In silico modeling of acidic (CH2COOH) or basic (CH2NH2) functionalized silica surfaces has been carried out by means of a density functional approach based on a gradient-corrected functional to provide insight into the characterization of experimentally functionalized surfaces via a plasma method. Hydroxylated surfaces of crystalline cristobalite (sporting 4.8 OH/nm2) mimic an amorphous silica interface as unsubstituted material. To functionalize the silica surface we transformed the surface Si-OH groups into Si-CH2COOH and Si-CH2NH2 moieties to represent acidic/basic chemical character for the substitution. Structures, energetics, electronic, and vibrational properties were computed and compared as a function of the increasing loading of the functional groups (from 1 to 4 per surface unit cell). Classical molecular dynamics simulations of selected cases have been performed through a Reax-FF reactive force field to assess the mobility of the surface added chains. Both DFT and force field calculations identify the CH2NH2 moderate surface loading (1 group per unit cell) as the most stable functionalization, at variance with the case of the CH2COOH group, where higher loadings are preferred (2 groups per unit cell). The vibrational fingerprints of the surface functionalities, which are the ?(C=O) stretching and ?(NH2) bending modes for acidic/basic cases, have been characterized as a function of substitution percentage in order to guide the assignment of the experimental data. The final results highlighted the different behavior of the two types of functionalization. On the one hand, the frequency associated with the ?(C=O) mode shifts to lower wavenumbers as a function of the H-bond strength between the surface functionalities (both COOH and SiOH groups), and on the other hand, the ?(NH2) frequency shift seems to be caused by a subtle balance between the H-bond donor and acceptor abilities of the NH2 moiety. Both sets of data are in general agreement with experimental measurements on the corresponding silica-functionalized materials and provide finer details for a deeper interpretation of experimental spectra.